We have set up the salutation field as an option set (options: Herr / Frau / Divers). I have read that option sets aren't supported for use in dynamic text. Option sets are supported in conditions, so an inline condition can be used to output option values in messages (see <https://learn.microsoft.com/en-us/dynamics365/marketing/real-time-marketing-personalization#limitations).
As described here (https://learn.microsoft.com/de-de/dynamics365/marketing/real-time-marketing-personalize-inline-conditions) we have tried to add our salutation option set in the email editor. This didn't work.